Observation of Antiferromagnetic Spin-Flop Transition in λ-type BETS Salts Using AFM Microcantilever

Antiferromagnetic spin-flop transitions in a series of λ- (BETS)₂FeBr _x Cl_4-x are observed using piezoresistive AFM microcantilever. The measurements are carried out on a tiny single crystal using a sample rotator and the easy axis changes with increasing the bromine content x. The Néel temperature and spin-flop transition field also rise with increasing the bromine content x, suggesting an enhancement of π-d interactions by replacement of chlorine with bromine atoms in this mixed-halide anion system.     

Particle-triggered pre-breakdown phenomena in atmospheric air gap under AC voltage

Corona discharge mechanism and breakdown voltage characteristics of air gaps in the presence of metallic particles were investigated including the relationship between the corona discharge mechanism and the phase resolved partial discharge patterns. These results are of interest for detection of foreign particles in gas insulated systems (GIS). The results with different shaped particles show that the corona mechanism depends on the particle shape and applied voltage. Moreover the corona discharges on both sides of the particle interfere with each other by inflow of charge carriers into the particle. The breakdown voltage is a minimum when the particle is in the vicinity of the electrode due to active interference of coronas. The phase-charge characteristics as the phase resolved partial discharge patterns vary with the particle shape. This suggests that the corona discharge mechanisms for all types of particles should be considered in the particle-detection method for GIS based on the phase resolved partial discharge patterns.     

Influence of hydrogen bonding on the viscosity of coal liquids

Viscosity, infrared, and proton magnetic resonance studies are reported on the SRC II process solvent (before fractionation), and its acid + neutral fraction, and on the interaction of these coal liquids with quinoline and triethylamine. The results obtained with the coal liquids and with several model compounds suggest that hydrogen bonding involving largely phenolic OH and nitrogen-containing bases, OH…N, gives rise to protontransfer complexes, O^?…^pHN, which is in part responsible for the viscosity and non-Newtonian flow of the coal liquids.     

Cytochrome P450 1B1 mRNA levels in peripheral blood cells and exposure to polycyclic aromatic hydrocarbons in Chinese coke oven workers

Cytochrome P450 1B1 (CYP1B1) is induced through the Ah receptor and is involved in the activation of polycyclic aromatic hydrocarbons (PAHs). To determine the validity of a quantitative analysis of CYP1B1 mRNA in peripheral human blood cells for the estimation of PAH exposure, a real-time quantitative polymerase chain reaction method was used to measure the relative levels of CYP1B1 mRNA in 37 Chinese coke oven workers and 13 control workers. A large inter-individual difference in the levels was observed. The average level of the CYP1B1 mRNA in workers at the top work site, where the PAH exposure level from the coke ovens was highest, was significantly higher than in workers at the middle site (P<0.01) or the controls (P=0.02). A non-significant positive correlation was found between the CYP1B1 mRNA levels and urinary 1-hydroxypyrene (R=0.22, P=0.13), and a significant correlation between these mRNA levels and urinary cotinine (R=0.33, P=0.02). It was interesting that a significant positive correlation between CYP1B1 mRNA and 1-hydroxypyrene was observed in subjects with the Leu/Leu type of CYP1B1 Leu432Val polymorphism (R=0.33, P=0.02, n=38) and a non-significant correlation in subjects with the Leu/Val and Val/Val types (R=-0.36, P=0.25, n=12), although the number of subjects in this strata analysis was small. Our preliminary study suggests that PAH exposure in coke ovens and smoking maybe associated with CYP1B1 mRNA levels in peripheral blood cells although mRNA is generally unstable and could be expressed following exposure to other agents.     

Solving and visualizing nonlinear parametric constraints in control based on quantifier elimination

We present a new method with a software tool for parametric robust control synthesis by symbolic-numeric computation. The method is a parameter space approach and it is especially effective for analysis and design of fixed-structure controllers of rational type, which encompass PI and PID controllers. The real quantifier elimination (QE), which is one of the recent progresses in the symbolic computation, plays a key role in our development. The QE-based approach can uniformly deal with a lot of important design specifications for robust control such as frequency restricted H _∞ norm constraints, stability (gain/phase) margin and stability radius specifications, and pole location requirement by reducing such specifications to a particular type of formulae called a “sign definite condition (SDC)”. This is also useful for improving the efficiency of QE computations since we can utilize an efficient QE algorithm specialized to the SDC using the Sturm-Habicht sequence. We have developed a MATLAB toolbox for robust parametric control based on a parameter space approach accomplished by QE. The QE-based parameter space approach and numerical simulation of performances for specific controller parameter values taken from a controller parameter space are integrated conveniently in our toolbox with the assistance of a graphical user interface (GUI). With our toolbox the feasible regions of controller parameters are visualized in a parameter space for the controllers with three or two parameters. This enables control engineers to achieve multi-objective robust controller synthesis smoothly. We also discuss how to merge the numerical computation and the symbolic operation to make our new design methods more efficient in practical control design.     

Crystal structure and optical property of TiO2 gels and films prepared from Ti-edta complexes as titania precursors

Titania gel and films were prepared from Ti-edta complex solutions as new ceramic precursors, and their crystal structures and optical properties were investigated. Anatase appeared in the gel at firing temperatures between 450 and 500°C, and was transformed to rutile at temperatures between 550 and 600°C. This low transformation temperature is presumed to be due to the small crystalline size and micro pores in the gel. Refractive indices of the films were higher than those of the films prepared by a sol-gel process at firing temperatures above 700°C. These high values were caused by the rutile phase in the TiO₂ films.     

High power and low optical feedback noise AlGaAs single quantum well lasers

GaAs-AlGaAs single quantum well self-aligned lasers have been developed for optical disc recording. The lasers emitting at 834 nm have realised low optical feedback noise as well as high output power. The lasers have shown less than -130 dB/Hz relative intensity noise at 3 mW, and stable 50 mW operation (over 500 hours at 50 degrees C ambient).<>     

Characteristics of barium ferrite tape for magnetic contactduplication

The magnetic properties and electromagnetic characteristics of Ba-ferrite tape for R-DAT magnetic contact duplication (MCD) were investigated. The tapes employed Ba-ferrite particles averaging 0.06 μm in diameter with an aspect ratio between 4 and 5. Ba-ferrite tapes were prepared with perpendicular, longitudinal, and no orientation, and their MCD and ring-head recording (RHR) characteristics were compared. Several distinctive characteristics were observed in MCD, and the desirability of perpendicular orientation at short wavelengths in MCD applications is clear. Tilted orientation was also investigated, and its output level was similar to that of perpendicular orientation in MCD, while in RHR it proved superior to perpendicular orientation in the short wavelength region. The magnetization mode of the slave tape was studied by waveform analysis using the FFT method and in conjunction with the tapes' magnetic properties, such as uniaxial anisotropy energy, remanence coercivity, and squareness ratio     

Crystallization and preliminary crystallographic data of the alpha-amylase inhibitors, Haim I and Paim I

Two proteins that act as alpha-amylase inhibitors, Haim I and Paim I, were crystallized and preliminary X-ray diffraction studies on them were carried out. We also sequenced Haim I prepared from Streptomyces griseosporeus YM-25 and confirmed that it is composed of 78 amino acid residues. Crystals of Haim I were grown from ammonium sulfate solution mixed with ethanol by the vapor diffusion technique. The crystals grew as hexagonal bipyramids and diffracted X-rays beyond 2.0 A resolution. They belong to the space group P6(1)22 (or P6(5)22) with unit cell dimensions of a = b = 36.7 A, c = 192.4 A, and contain one molecule per asymmetric unit. Paim I, a protein of 39 amino acid residues produced by Streptomyces corchorusii, was crystallized under similar conditions to Haim I. The crystals diffracted X-rays beyond 2.5 A. They belong to the space group P4(1)2(1)2 (or P4(3)2(1)2) with unit cell dimensions of a = b = 65.4 A, c = 96.1 A, and contain three molecules per asymmetric unit.     

Aggregation behavior of halato-telechelic ionomers in a low-polarity solvent

Summary The solution behavior of halato-telechelic ionomers (polybutadiene with carboxylate end groups) in a low-polarity solvent (tetrahydrofuran (THF)) was studied. It was shown that the degree of aggregation can be expressed as a function of polymer concentration by an empirical equation, DA - 10_c, where DA is the degree of aggregation, c is polymer concentration, and is a constant relating to the rate of aggregation with polymer concentration. It was also shown that the aggregation effect of the Na salt was larger than that of the Cs salt, which was reflected in the value of .